Approximately 1.1 to 1.2 cm in diameter. This is a set of 5 back buttons. (These are change buttons for attaching the back of student uniform buttons, with a black plastic base and a cherry blossom mark.) Replacing the back buttons is easy, even for children. The 5 back buttons will be placed in a pouch and sent via Japan Post's Mini Letter service in simple packaging. There is no tracking number, so you cannot track the package. There is also a listing that uses Yu-Packet Post Mini, which allows for tracking. Please search for the product name: "Back Button Standard Student Uniform - Black Plastic Cherry Blossom Change Button Set of 5 - New". Delivery will be by mail slot, not hand delivery. Items for which payment is confirmed by 12:00 PM (noon) will be shipped the same day. (There are basically no days when we cannot ship, but if there is an urgent matter that prevents us from shipping, we will ship the next day.) Depending on your area, delivery to your mailbox usually takes 1-3 days after the shipping date. For more details, please check the estimated delivery time from Osaka via Mini Letter on the internet. *New product. *Free shipping.